Flame retardant polymer composition

ABSTRACT

A flame retardant polymer composition comprises a major amount of a poly (1, 3 imidazolidine-2, 4, 5 trione) which has the following structure:   where n1 is an integer &gt;10 and where R3 is a hydrocarbon or substituted hydrocarbon group and a minor but effective amount of a compound selected from the group consisting of phosphonates and phosphates having the following structure:   and

United States Patent 1 Johnson et al.

(451 Aug. 26, 1975 FLAME RETARDANT POLYMER COMPOSITION [75] Inventors:Burnett H. Johnson, Baytown, Tex.;

Edward F. Johnson, Towa City, Iowa [73] Assignee: Exxon Research andEngineering Company, Linden, NJ.

22 Filed: Feb. 4, 1974 211 Appl. No.: 439,179

Related US. Application Data [63] Continuation of Ser. No. 284,321, Aug.28, I972,

abandoned.

[52] [1.5. CI.. 260/45.7 PS; 260/45.7 P; 260/77.5 R; 260/775 CH; 260/775SS; 260/858 OTHER PUBLICATIONS Hilado, Flammability Handbook forPlastics," I969, pg. 85.

Primary Examiner-Donald E. Czaja Assistant Examiner-R. A. WhiteAttorney, Agent, or Firm-David A. Roth [57] ABSTRACT A flame retardantpolymer composition comprises a major amount of a poly (I, 3imidazolidine-2, 4, 5 trione) which has the following structure:

where n is an integer 10 and where R; is a hydrocarbon or substitutedhydrocarbon group and a minor but effective amount of a compoundselected from the group consisting of phosphonates and phosphates havingthe following structure:

and

where -R is an aryl or a halogenated aryl group as exemplified but notlimited by and halogenated derivatives thereof;

R is a halogenated aryl group comprised of the same aryl groups aslisted for R;

R is a phenyl group;

n is an integer equal to or greater than I.

6 Claims, No Drawings FLAME RETARDANT POLYMER COMPOSITIONCROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation ofapplication Scr. No. 284,321 filed Aug. 28, 1972, now abandoned.

This application is related to Ser. No. 29.657 filed Apr. I7, [970, nowU.S. Pat. No. 3,661,859.

BACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention is directed to a flame-retardant polymer composition. Moreparticularly, the invention is directed to a composition comprised ofpoly (l, 3- imidazolidinc -2, 4, 5-trioncs) and phosphonates orphosphates which resist burning. In its more specific aspects, theinvention is concerned with a polymer composition of the aforementionedpolymers and halogenated phosphonates or phosphates.

2, Description of the Prior Art.

The use of phosphonates or phosphates as flame retardants for polymersand other flammable materials is well known, For example, flameretardants have been added to polyolefins. However, it has been foundthat ordinarily large amounts of flame retardants must be added to theusual polymer before any great resistance to flammability is conferredthereto. This, not only is expensive but also detracts from the qualityof the polymer. especially when it is in the form of a film.

It has now been found that the flame retardance of poly (l,3-imidazolidine triones), especially in film form, may be rendered flameretardant by addition thereto of halogenated phosphonates or phosphatesin small amounts as compared to the amounts usually employed for otherpolymers.

The following prior art was considered relative to this invention:

U.S. Pat. Nos. 3,576,793, 3,560,432, 3,557,053,

3,549,480, 3,547,878, 3,544,509, 3,539,53]. 3,530,083, 3,489,722,3,47I,427, 3,468,980, 3,463,837, 3,412,070, 3,421,052, 3,349,150,3,329,65l, 3,194,795, 3,I62,6l0, 3,l45,l77, 3.] 15,466, 3,058,941,3,020,306, 3,020,256, 3,014,954. 3,0l4,95l, 3,0l4,956, 3,0I4,944,2,999,823, 2,959,568, 2,934,507, 2,877,204, 2,856,369, 2,739,952,2,627,521, 2,5l6,l68, 3,547,897, 3.59l.562, 3,239,482, 3,609,I l3

('liemit'ul & Engineering News. OCt. I8. I97 I page 16; and ModernPlastics. June, l97l, pages 50-5l.

SUMMARY OF THE INVENTION The present invention may be briefly describedand summarized as involving a flame retardant polymer composition of amajor amount of a polymer which is characterized by repeating unitswhich contain l, 3 -imidazolidinc 2, 4, 5 trione l, 3 diyl ring and anorganic moiety, R which may be aromatic. aliphatic, alicyclic, thesesame groups which are substituted, and mixtures thereof. Examples of.but not limited to. such groups are:

and

(R 0 P o where R is an aryl or a halogenated aryl group as definedbefore;

R is an aryl or a halogenated aryl group as defined before;

R is a phenyl group;

n is an integer equal to or greater than I.

VARIABLES OF THE INVENTION The polymer of the present invention is apoly (I, 3 imidazolidine 2, 4, 5 trione) which contains the l, 3,-imidazolidine -2, 4,5 -trione 1, 3, diyl ring of the structure:

U i N N 2 I II ll These polymers are described in allowed Ser. No.29,657; U.S. 3,591,562; and U.S. 3,609,113 all of which are incorporatedherein by reference.

As examples of such polymers may be mentioned:

0 II R N N- l l (I C n II ll 0 0 where R, is as defined before such asbut not limited to:

e ro +6 or mixture thereof and n is an integer 10.

The halogenated mono aryl group is preferably brominated aryl, butchlorinated aryl or iodine substituted mono aryl may be used. When thechlorine or iodine substitute mono aryl is employed, more of thephosphonate or phosphate may be required than when the bro minesubstituted mono aryl is used. For example. with the brominated monoaryl. the phosphoriate or phosphate may be employed within the rangefrom about 2.57! to about 15% by weight. preferably about 2.59? to aboutl0.07r by weight. whereas with the other halogens as substituents. theamount of phosphonate or phosphate in the flame retardant compositionmay be in the upper part of the range. say from about 10% to about 15?!by weight.

In preparing the Class 1 and 11 phosphonates. a mixed Friedel CraftsCatalyst or a weak Lewis acid may be used as illustrated in the exampleswhich follow.

The flame retardance of certain polymers may be improved by theincorporation of aromatic phosphonates or phosphates described inClass 1. Class 11. and Class Ill. Further improvement in flameretardance may be possible by combination or mixtures of thephosphonates and phosphates described below with each other and withother known flame retardants as shown in the prior art.

Unusually low levels ofthe phosphates and phosphonates described belowgive unexpected improvement in the flame retardance ofimidazolidinetrione polymers and of paramount importance. the phosphatesand phosphonates are compatible with imidazolidinetrione polymers andthus do not embrittlc film made there from.

The phosphonates described in Class 1 or Class 11 are prepared by thereaction ofa halogenated monoor di functional phenol with dichlorophenylphosphine oxide. The phosphates described in Class 111 are prepared byreacting monoor diphenols with phosphorous pentaehloride.

Class l. Phosphonatcs prepared from monofunctional phenols.

where R is an aryl or halogenated aryl group as defined before. R is aphenyl group.

Example; Bis(2.4, 6-tribromophenyl) phenylphosphonate Class 11.Phosphonates and Polyphosphonates prepared from difunetional phenols llH()-R,- o -P-() l e A011 where R, is an aryl or halogenated aryl groupas defined before;

R is a phenyl group: n is an integer equal to or greater than 1.

Example: Poly ]oxy(2.6-dibromol.4-phenylenel isopropylidcne-(2.6dibromo1.4-phenylene) (phenyl phosphonylidcne Br Br CH 0 E c I C2 ll 9 0-(i O- P n Br CH v r Class III. (R o}. P o where R is an aryl orhalogenated aryl group as defined before. The following examplesillustrate. but do not limit. this invention.

EXAMPLE l in a flask equipped with a condenser and an addition funnel.700 grams of 2.4.6tribromophenol (0.21 1 moles) and 1.0 grams ofmagnesium chloride (0.0105 moles) were dissolved in 40 millilitersofdiphenyl ether at C. under a nitrogen atmosphere. After the catalysthad dissolved. 19.5 grams of dichlorophenyl phosphine oxide (0.100moles) were added dropwise. The diphenyl ether solution was heated at C.for 16 hours under a stream of nitrogen. After the reaction had cooledto room temperature, the his (2. 4, 6- tribromophenyl) phenylphosphonatewas precipitated by adding the diphenyl ether solution to 400milliliters of 5% diethyl ether in hexane. The precipitate. afterwashing with hexane and then with methanol. yielded 621 grams (79.2%

EXAMPLE 11 In a resin pot equipped with a condenser. an overheadstirrer. and an addition funnel. 857.2 grams of 2.4.6-tribromophcnol(2.59 moles) and 5.0 grams of magnesium chloride (0.0525 moles) weremelted at l 15 C. under a nitrogen atmosphere. To the melt. 250 grams ofdichlorophenylphosphine oxide (1.28 moles) were added dropwise over aperiod of 25 minutes. The melt was stirred and heated at for 17 hoursunder a stream of nitrogen to remove the hydrogen chloride evolved.After cooling the melt to 130 C., the reaction flask was placed under avacuum and heated to 175 C. for an additional 21 hours. Sublimed phenol.which collected in the top of the resin pot. was removed. The yield ofthe bis(2.4,6-tribromophenyl) phenylphosphonate was 963 grams (95.8%

EXAMPLE lll Using the same procedure used in Example I. 30.0 grams ofpcntabromophenol (0.0613 moles) and 0.50 grams of magnesium chloride(0.00525 moles) were suspended in 40 milliliters ofdiphenyl ether. Afterthe suspension was heated to 105 C.. 5.85 grams ofdichlorophenylphosphine oxide (0.030 moles) were added dropwise. Thesuspension was heated to C. over a period of 18 hours and worked up bythe procedure used in Example 1 to yield 30.7 grams (93.0% of his(pentabromophenylj phenylphosphonate.

EXAMPLE 1V Llsing the same procedure used in Example II. 56.6 grams of4.4'-isopropylii.lencbis(3.54libromophenol) (0.l moles) were heated tol85C. To the unmelted solids. 9.75 grams of dichloruphenylphosphineoxide (0.05 moles) were added dropwise to give a dough-like material.This material was heated to 2l5C. for 6 hours under a stream of nitrogenand then worked up by the procedure used in Example 1 to yield 600 grams(95.7% of poly [oxy( 2,6-dibromo-l .4- phenylene )isopropylidene-(3.5-dibromo-l .4- phenylene)(phenyl phosphonylidenel].

EXAMPLE V Using the same procedure used in Example I. 202.4 grams of4.4'-sulfonylbis(3.5-dibromophenol) (0.372 moles) and 2.0 grams ofstarmous chloride (0.0l moles) were dissolved in 500 milliliters ofdiphenyl ether under a nitrogen atmosphere. To this solution. 74.0 gramsof dichlorophenylphosphine oxide (0.380 moles) were added dropwise. Thecombined solution was heated 24 hours at 235 C. and 24 hours at 220under a nitrogen stream. The final 24 hours at 235 C. were conductedunder a vacuum. After cooling. the diphenyl ether solution wasprecipitated into methanol to yield 202 grams (8].67?) of the compoundhaving the structure shown in the table which follows.

EXAMPLE VI Using the same procedure as in Example I, 74.0 grams ofdichlorophenyl phosphine oxide (0.38 moles) were reacted with 202.4grams of 4.4'-isopropylidene bis (3.5-dibromophenol) (0.37 mols) in 500milliliters of phenyl ether using 2.0 gms. of stannous chloride ascatalyst. After 72 hours at 220C. the product was precipitated andrecovered by pouring reaction mixture in methanol and filtering. Theyield was 202 grams corre sponding to an 82% yield. The structure of thepoly meric phosphonatc is:

EXAMPLE Vll To a stirred flask equipped with a condenser were added l7grams (0.1 molsl of p-phcnyl phenol. 5.4 grams (0.026 molslvofphosphorous pentachloridc and 75 cc of carbon tetrachloride. A slowstream of N was used as a purge to remove the HCl from the flask andinto a caustic scrubber containing phcnolphthalcin and an amount of NaOHequivalent to the theoretical amount of HCl that would be liberated bycomplete reaction. The temperature was gradually raised to 77 C. andafter four hours all caustic in the caustic scrubber was neutralized.After cooling to room temperature. water was introduced continuouslyinto the flask while stirring vigorously until hydrolysis was completeas shown by the neutrality of the water. The product was a whiteprecipitate suspended in the water phase. This was recovered and weighedl3.3 grams corresponding to a 92% yield based on phosphorouspentachloride. The structure of the phosphate is:

EXAMPLE Vlll Fifty grams of 2.4.6. tribromophenol (0.15 mols). 8.3 gramsof phosphorous pentachloride (0.04 mols) and cc of carbon tetrachloridewere put into a stirred flask fitted with a reflux condenser and havingan N purge into a caustic scrubber as described in Example VII. Thetemperature was gradually raised to 70 C. After six hours the causticscrubber was neutralized indicating complete reaction. The product washydrolyzed and recovered as described in Example VII. The yield was 39.2grams of white product corresponding to 95% of theoretical based onphosphorous pentachloride. The structure of the phosphate is:

Br 0 P=O The table below shows the flame retardant properties of theabove compounds in thin films (2.8 to 3.8 mils) of poly(4. 4'-methylene-diphenyl-l .3-imidazolidine- 2.4.5 trione). The films wereprepared by dissolving the polymer and a low percentage of flameretardant (2.5 to 10.0%) in dimethyl sulfoxide. The films were thensolution cast. dried and cut into 6 by 4 inch strips for testing. Astandard oxygen index test ASTM D-2863- 70 was used to determine theeffectiveness of flame re tardants. The following results were obtainedand are to be compared to a 207 oxygen index for base polymer withoutany additives.

Weight Percent ()sygen Index Example No. Formula for Flame RetardantFlame Retardant Percent 2.5 26.7 16; ll Br U-P- O Br 5.0 36.0 (.i mo47.5

Bl Br 0 Br Br lll Br flggo i o B1 2.5 111,-:

Br Br cnllh 5, Dr

B ('llL. Br t) w g c 0% P 2 s :m

" ell. iai.

-Continued Example No. Formula for Flame Retardant Flame RetardantPercent O Br Bl v Z/ s{ i-o P 2 s 32 2 Br ll I II VI -C OP Incompatiblek G I Brittle Film CH, n

vtl )0 P=0 5.0 24.0 3 ton 29.0

Ir viii Br 0 -P=O 7.5 27.3

Besides the phosphonates and phosphates illustrated. 0 otherphosphonates and phosphates which are useful are those where R and R,are

R N N l l i CC H l O 0 Br V DO 430 0 Br Br Q Q r Br The oxygen index isa well known test for determining the flammability of plastics and is astandard method of test ASTM Designation D-2863-70. A high oxygen indexindicates a greater resistance to flammability.

It will be clearfrom the data in Example V that as little as 2.5% byweight of the several phosphonates and 5.0% of the phosphates increasedthe oxygen index to over 24. whereas 5.0 and l0.07( by weight increasedthe oxygen index of the phosphonate containing film to 36.0 and 47.5.Similar results are obtained with the phosphates. This may be comparedwith the base polymer of 20.7 oxygen index and the fact that the flameretardant compositions of the present invention do not require highloading of the particular phosphonates or phosphate used on theparticular polymer. In the Mod- :rn Plastics article supra. polyolefinsrequired additive oadings up to 3071 to achieve the desired degree ofWame retardancy.

Thus. the present invention is new useful and unobvious.

The nature and objects of the present invention havng been fullydescribed and illustrated and the best node and embodiment contemplatedset forth. what we wish to claim as new and useful and secure by Let-Lers Patent is:

l. A flame retardant composition comprising:

A major amount of a polymer selected from the group of poly(l.3-imidazolidine-2.4.S-triones) having the following structure:

where n 1 it) and R a hydrocarbon or substituted hydrocarbon group and aminor amount effective to improve the flame retardancy of said polymer,but insufficient to cause embrittling of said polymer. of

wherein n is an integer equal to or greater than I which is polyoxy(2,6-dibromo-l .4 phenylcne) sulfonyl (2, 6 dibromo-l, 4 phenylcne)(phenyl phosphonylidene) when n is greater than 1.

2. A composition in accordance with claim 1 in which the compound is inan amount front 2.571 to about 10.0% by weight.

3. A composition in accordance with claim 1 in which the R; group in thepolymer is 4.4'-diphenyl methane.

4. A composition according to claim I which is in the shape of a film.

5. A composition according to claim I wherein said polymer and saidcompound are soluble in the same solvents.

6. A composition according to claim 4 in which said film has been formedby casting a solution of said polymer and said compound.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 701,847 Dated October 31, 192?.

Inventor(s) Sakae Miyauchi et a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

After the listing of the inventors insert Assignee: Nihon DenshiKabushiki Kaisha Signed and sealed this 1st day of May 1973.

SEAL) Attest:

BDLJA ED M. FLETCHER, JR. ROBERT GOTTSCHALK i tttesting OfficerCommissionerof Patents U 5 GOVERNMENT HUNTING OFFICE 7 I969 O-366-334

1. A FLAME RETARDANT COMPOSITION COMPRISING: A MAJOR AMOUNT OF APOLYMERSELECTED FROM THE GROUP OF POLY (1,3-IMIDAZOLIDINE-2,4,5-TRIONES) HAVINGTHE FOLLOWING STRUCTURE:
 2. A composition in accordance with claim 1 inwhich the compound is in an amount from 2.5% to about 10.0% by weight.3. A composition in accordance with claim 1 in which the R3 group in thepolymer is 4,4''-diphenyl methane.
 4. A composition according to claim 1which is in the shape of a film.
 5. A composition according to claim 1wherein said polymer and said compound are soluble in the same solvents.6. A composition according to claim 4 in which said film has been formedby casting a solution of said polymer and said compound.